3onedata CAN485 User Manual page 24

Make reference to the segment transfer protocol message segment in DeviceNet. Segmented message format are
shown in (to extend the frame as an example, standard frame is just a different length of the frame ID, other the
same format), transmission of Modbus protocol can from "data 2" start byte, if the file is greater than 7 bytes, then
the rest of the file within the volume according to the paragraphing continue the conversion until completion of the
conversion.
Frame information
Frame ID1
Frame ID2
Frame ID3
Frame ID4
Data 1
Data 2
Data 3
Data 4
Data 5
Data 6
Data 7
Data 8
Segment Mark: The message is segmented message or a separate message. If the value of 0 is a separate message,
a value of 1 is a message in Segment.
Segment type: indicate that the packet is not segmented, the first segment, the middle segment, or the last segment.
Position
00
01
10
11
Segment Counter: Mark each segment, the segment in the message number, if it is a 'N' segment, then counter value
is 'N'. So at the receiver can verify whether the segment is lost, so the sectional counting ranges: 1-63 (bit 0~5).
Table 6.3.1.1 CAN2.0 Extended Frame Format
7 6
FF RTR
x x
Segment Mark
Table 6.3.1.2
Type
No segment That message does not segment
If the segment counter has a value of 0, so
The first segment
this is the first stage in the series
The middle segment That this is an intermediate segment
The last segment Mark the last segment
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5 4 3
x x DLC（data length）
x ID.28—ID.24
ID.23—ID.16
ID.15—ID.8
ID.7—ID.0
Segment Counter
Character 1
Character 2
Character 3
Character 4
Character 5
Character 6
Character 7
Segment type position
Describe
2 1 0
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